1. Field of the Invention
This invention relates to circuit interrupters of the type having a bimetallic thermal conduit trip element and a magnetic instantaneous element, and more particularly, to circuit breakers for distribution transformers to control moderate power distribution on feeder circuits.
2. Description of the Prior Art
Transformers used in power distribution systems are generally associated with a protective device which prevents or limits current overload damage to the transformer and its associated apparatus. A completely self-protected transformer includes a circuit interrupter on the secondary or low voltage side to protect against damage due to overload current. The secondary circuit interrupter disconnects the transformer from its load if the load current becomes dangerously high. The secondary circuit interrupter is normally disposed beneath the insulating oil of the transformer to take advantage of its superior dielectric strength.
Commonly used circuit interrupters often incorporated a bimetal thermal trip and an instantaneous magnetic trip. For high overload currents it is desirable that the circuit interruption be completed as rapidly as possible after initiation.